鄂尔多斯断块地壳电性结构  

ELECTRIC STRUCTURE OF THE CRUST BENEATH THE ORDOS FAULT BLOCK

作　　者：赵国泽[1] 詹艳[1] 王立凤[1] 王继军[1] 汤吉[1] 陈小斌[1] 肖骑彬[1] 

机构地区：[1]中国地震局地质研究所,北京100029

出　　处：《地震地质》2010年第3期345-359,共15页Seismology and Geology

基　　金：国家自然科学基金(40374032;40534023);中国地震局地质研究所基本科研业务专项(DF-IGCEA0607117);国家公益性地震行业专项(2008419010);国家重点基础研究发展计划项目(2004CB418402)共同资助

摘　　要：鄂尔多斯断块作为新生代以来的稳定块体,其中下地壳内是否存在低阻层一直受到关注。基于穿过鄂尔多斯断块大地电磁剖面的观测资料,利用新的数据处理和解释技术,对鄂尔多斯断块的地壳结构进行了整体研究,发现鄂尔多斯断块的地壳具有成层性结构特点,并在约20km深度存在低阻层,推测它是由流体引起的电阻率降低。在断块东、西两侧的构造活动区,其地壳内不存在成层性电性结构,其中的低阻带可能与地壳内的滑脱带(或韧性剪切带)有关。鄂尔多斯断块和周围地区地壳电性结构的不同特点,对于分析不同地块的变形和地震活动性等有一定价值。The Ordos fault block is a stable block since the Cenozoic time. Whether low-resistivity layers exist in the middle and lower crust of this kind block is an open question. This work attempts to reveal the entire crustal structure of the Ordos fault block based on interpretation of magnetotelluric data col- lected along the profile across this region. The result shows that a layered structure characterizes the crust of the Ordos fault block, with a low-resistivity layer at depth of about 20km, presumably associat- ed with fluids there. On contrast, in the areas of active tectonics in the east and west of the fault block, there is no such layered electric structure in crust, while the low-resistivity zones may be related with the detachments（or ductile-shear zones）in crust. The difference in electric structure of crust between the Ordos fault block and neighboring areas is of significance to the analysis of activity and deforma- tion in varied blocks.

关 键 词：鄂尔多斯断块 大地电磁 地壳结构 低阻层 流体 

分 类 号：P631[天文地球—地质矿产勘探]